#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define rsort(a) {sort(all(a));reverse(all(a));}
#define pb emplace_back
#define lb(v,k) (lower_bound(all(v),(k))-v.begin())
#define fi first
#define se second
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
#define dame(a) {cout<<a<<endl;return 0;}
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vvvp=vector<vvp>;
using vb=vector<bool>;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
const ll inf=1001001001001001001;
#include "dreaming.h"
int travelTime(int n,int m,int L,int a[],int b[],int t[]){
vvp g(n);
rep(i,m){
g[a[i]].pb(b[i],t[i]);
g[b[i]].pb(a[i],t[i]);
}
vb visited(n,false);
vi u(n),d(n);
function<void(ll,ll)> dfs=[&](ll i,ll p){
visited[i]=true;
for(auto x:g[i])if(x.fi!=p){
dfs(x.fi,i);
chmax(d[i],d[x.fi]+x.se);
}
};
ll mi;
function<void(ll,ll)> dfs2=[&](ll i,ll p){
vi ma;
for(auto x:g[i])if(x.fi!=p)ma.pb(d[x.fi]+x.se);
if(ma.size()){
vi l(ma.size()),r(ma.size());
l[0]=0;
REP(i,1,l.size())l[i]=max(l[i-1],ma[i-1]);
r.back()=0;for(ll i=r.size()-1;i>0;i--)r[i-1]=max(r[i],ma[i]);
ll c=0;
for(auto x:g[i])if(x.fi!=p){
u[x.fi]=u[i]+x.se;
chmax(u[x.fi],max(l[c],r[c])+x.se);
c++;
}
}
for(auto x:g[i])if(x.fi!=p)dfs2(x.fi,i);
chmin(mi,max(u[i],d[i]));
};
vi v;
rep(i,n)if(!visited[i]){
mi=inf;dfs(i,-1);
dfs2(i,-1);
v.pb(mi);
}
rsort(v);
ll ans=0;rep(i,n)chmax(ans,max(d[i],u[i]));
if(v.size()>=2)chmax(ans,v[0]+v[1]+L);
if(v.size()>=3)chmax(ans,v[1]+v[2]+L*2);
return (int)(ans);
}/*
int main(){
int a[10],b[10],t[10];
int n,m,l;cin>>n>>m>>l;
rep(i,m)cin>>a[i]>>b[i]>>t[i];
out(travelTime(n,m,l,a,b,t));
}*/
